Obesity is a difficult to treat chronic condition defined by a body mass index (BMI=mass/height2[kg/m2]) greater than 30. For obese persons, excessive weight is commonly associated with increased risk of cardiovascular disease, diabetes, degenerative arthritis, endocrine and pulmonary abnormalities, gallbladder disease and hypertension. Additionally, such persons are highly likely to experience psychological difficulties because of lifestyle restrictions such as reduced mobility and physical capacity, due to back pain, joint problems, and shortness of breath. In severe cases, this can contribute to absenteeism and unemployment. Moreover, impairment of body image can lead to significant psychological disturbances. Repeated failures of dieting and exercise to resolve the problem of obesity can result in feelings of despair and the development of clinical depression.
Bariatric surgery is often recommended for persons suffering from morbid obesity. Preferably, the invasive treatment is accompanied by changes in lifestyle, such as improved regulation of eating habits and an appropriate exercise regimen. Such lifestyle changes are dependent upon the self-discipline and cooperation of the subject.
A book entitled, Textbook of Gastroenterology, 3rd edition, edited by Yamada (Lippincott, Williams & Wilkins), which is incorporated herein by reference, includes, in Chapter 10 thereof, a description of the physiology of gastric motility and gastric emptying.
An abstract entitled, “Gastric myoelectrical pacing as therapy for morbid obesity: Preliminary results,” by Cigaina et al., retrieved on Dec. 24, 2000 from the Web-site http://www.med-online.com/transneuronix/Product/abstract.htm, which is incorporated herein by reference, describes a method for applying monopolar and bipolar gastric stimulation to achieve weight loss.
An abstract entitled, “Implantable gastric stimulator (IGS) as therapy for morbid obesity: Equipment, surgical technique and stimulation parameters,” by Cigaina et al., retrieved on Dec. 24, 2000 from the Web-site http://www.med-online.com/transneuronix/Product/abstract.htm, which is incorporated herein by reference, describes techniques of electrical signal therapy designed to treat obesity.
PCT Publication WO 05/087310 to Harel et al., which is assigned to the assignee of the present application and is incorporated herein by reference, describes a method for glucose level control including providing at least one electrode adapted to apply an electric field to a pancreas, and applying an electric field to the pancreas using said at least one electrode such that blood glucose levels are significantly reduced and blood insulin levels are not significantly increased compared to a regular insulin response in a same person. In an embodiment, the electric field is applied using electrodes on opposite sides of the stomach, so that a main conductive pathway between the electrode, which cannot pass through the hollow of the stomach, circumvents the stomach and passes through a portion of the pancreas. Optionally, the electric field has little or no effect on other organs, such as the stomach.
PCT Publication WO 04/066903 to Gross et al., which is incorporated herein by reference, describes apparatus for drug administration, including an ingestible capsule holding the drug. An environmentally-sensitive mechanism is adapted to change a state thereof responsive to a disposition of the capsule within a gastrointestinal tract of a subject. A driving mechanism, in response to a change of state of the environmentally-sensitive mechanism, is adapted to drive the drug directly through an endothelial layer of the gastrointestinal tract. In an embodiment, the driving mechanism includes an electrode. In an embodiment, the capsule includes self-expansible portions, which, for some applications, are covered with electrodes for stimulating the walls of the gastrointestinal tract.
PCT Publication WO 05/009288 to Burnett et al., which is incorporated herein by reference, describes devices for intermittently and/or partially obstructing a pyloric valve. The devices generally include a support portion for preventing the device from passing through the pyloric valve and a tissue engagement portion for contacting tissue adjacent the pyloric valve to obstruct the valve. Some embodiments also include a positioning member extending from the issue engagement portion for helping position the device for obstructing the valve. Some embodiments are deliverable into the stomach through the esophagus, either by swallowing or through a delivery tube or catheter. Some embodiments self-expand within the stomach, while others are inflated or otherwise expanded. Some embodiments include one or more electrodes coupled with the device and removably attachable to stomach tissue, or electrodes formed over a surface of the device.
U.S. Patent Application Publication 2004/0162469 to Imran and PCT Publication WO 04/091361 to Imran et al., which are incorporated herein by reference, describe a device and method for mapping, diagnosing, and treating conditions of the intestinal tract, such as bleeding, ischemic or necrotic tissue, and presence of certain chemicals or substances. The device includes a capsule that passes through the intestinal tract and senses optical characteristics. A map of optical characteristics is derived to diagnose the condition. The capsule or subsequently-passed capsules may treat, further diagnose, or mark the intestinal tract at a determined location along its length.
U.S. Patent Application Publication 2004/008023 to Imran et al., which is incorporated herein by reference, describes a device for diagnosing and treating gastric disorders. A functional device resides within the subject's stomach and is secured to the stomach wall by an attachment device. The functional device may be a sensor for sensing various parameters of the stomach or stomach environment, or may be a therapeutic delivery device. The functional device in one embodiment provides a device for gastric electrical stimulation, wherein stimulating electrodes are secured to the wall of the stomach by the attachment device or otherwise. One device described includes at least one stimulating electrode in electrical contact with the stomach wall; an electronics unit containing the electronic circuitry of the device; and an attachment mechanism for attaching the device to the stomach wall. The functional devices may be programmed to respond to sensed information or signals. An endoscopic delivery system delivers the functional device through the esophagus and into the stomach where it is attached the stomach wall. The endoscopic instruments attach or remove the attachment devices and functional devices from the stomach and may be used to assist in determining the optimal attachment location.
U.S. Patent Application Publication 2005/0021101 to Chen et al., which is incorporated herein by reference, describes a method for regulating gastrointestinal action in a subject using a stimulatory electrode and a sensor to provide retrograde feedback control of electrical stimulation to the GI tract. Also described is a method for reducing weight in a subject, using a stimulatory electrode and a sensor to provide retrograde feedback control of electrical stimulation to the stomach. Further described is a method for providing electrical field stimulation to a gastrointestinal organ, as well as a method of providing an electrical potential gradient in a gastrointestinal organ. Still further described is a method for stimulating the vagus nerve of a subject. Additionally, described is a method of placing a device in the gastrointestinal tract or wall of a subject from the exterior of the subject, using a needle to insert the device.
U.S. Pat. No. 6,754,536 to Swoyer et al., which is incorporated herein by reference, describes a GI tract stimulator and/or monitor and/or implantable medical device comprising a housing enclosing electrical stimulation and/or monitoring circuitry and a power source, and an elongated flexible member extending from the housing to an active fixation mechanism, which is adapted to be fixed into the GI tract wall. After fixation, the elongated flexible member bends into a preformed shape that presses the housing against the mucosa so that forces that would tend to dislodge the fixation mechanism are minimized. The device is fitted into an esophageal catheter lumen with the fixation mechanism aimed toward the catheter distal end opening, whereby the bend in the flexible member is straightened. The catheter body is inserted through the esophagus into the GI tract cavity to direct the catheter distal end to the site of implantation and fix the fixation mechanism to the GI tract wall. The device is ejected from the lumen, and the flexible member assumes its bent configuration and lodges the hermetically sealed housing against the mucosa. For temporary use, the fixation mechanism can be made of a material that is degraded by stomach acid over time to release the GI tract stimulator or monitor device and allow it to pass through the GI tract.
U.S. Pat. No. 6,129,685 to Howard, which is incorporated herein by reference, describes apparatus and methods for regulating appetite by electrical stimulation of the hypothalamus and by microinfusion of an appropriate quantity of a suitable drug to a distinct site or region within the hypothalamus.
U.S. Pat. No. 4,823,808 to Clegg et al., which is incorporated herein by reference, describes a method for treating obesity, including receiving a physiological measurement and generating audio and/or visual feedback for the subject to hear and/or see. The feedback is used for purposes of teaching behavior modification.
U.S. Pat. No. 5,868,141 to Ellias, which is incorporated herein by reference, describes an endoscopic stomach insert for reducing a subject's desire to eat.
U.S. Pat. No. 6,067,991 to Forsell, U.S. Pat. No. 5,601,604 to Vincent, U.S. Pat. No. 5,234,454 to Bangs, U.S. Pat. No. 4,133,315 to Berman et al., U.S. Pat. No. 4,416,267 to Garren et al., and U.S. Pat. Nos. 4,592,339, 5,449,368, 5,226,429 and 5,074,868 to Kuzmak, which are incorporated herein by reference, describe mechanical instruments for implantation in or around the stomach of an obese subject.
U.S. Pat. No. 5,690,691 to Chen et al., which is incorporated herein by reference, describes a gastric pacemaker for treating obesity and other disorders. The pacemaker includes multiple electrodes which are placed at various positions on the gastrointestinal (GI) tract, and deliver phased electrical stimulation to pace peristaltic movement of material through the GI tract.
U.S. Pat. No. 5,423,872 to Cigaina, which is incorporated herein by reference, describes apparatus for applying electrical pulses to the distal gastric antrum of a subject, so as to reduce the motility of the stomach and to thereby treat obesity or another disorder.
U.S. Pat. Nos. 5,188,104 and 5,263,480 to Wernicke et al., which are incorporated herein by reference, describe a method for stimulating the vagus nerve of a subject so as to alleviate an eating disorder.
U.S. Pat. Nos. 6,104,955, 6,091,992, and 5,836,994 to Bourgeois, U.S. Pat. No. 6,026,326 to Bardy, and U.S. Pat. No. 3,411,507 to Wingrove, which are incorporated herein by reference, describe the application of electrical signals to the GI tract to treat various physiological disorders.
U.S. Pat. No. 5,979,449 to Steer, which is incorporated herein by reference, describes an oral appliance for appetite suppression.
U.S. Pat. No. 4,975,682 to Kerr et al., which is incorporated herein by reference, describes apparatus for food intake regulation which is external to the body and which is based upon the voluntary cooperation of the subject in order to be effective.
U.S. Pat. No. 5,861,014 to Familoni, U.S. Pat. No. 5,716,385 to Mittal et al., and U.S. Pat. No. 5,995,872 to Bourgeois, which are incorporated herein by reference, describe methods and apparatus for stimulation of tissue, particularly gastrointestinal tract tissue.
PCT Patent Publication WO 02/082968 to Policker et al., entitled, “Analysis of eating habits,” which is incorporated herein by reference, describes apparatus and methods for detecting the occurrence of an eating event by a subject, and analyzing the quantity and characteristics of the food ingested.
U.S. Pat. No. 6,600,953 to Flesler et al., which is incorporated herein by reference, describes apparatus for treating a condition such as obesity. The apparatus includes a set of one or more electrodes, which are adapted to be applied to one or more respective sites in a vicinity of a body of a stomach of a subject. A control unit is adapted to drive the electrode set to apply to the body of the stomach a signal, configured such that application thereof increases a level of contraction of muscle tissue of the body of the stomach, and decreases a cross-sectional area of a portion of the body of the stomach for a substantially continuous period greater than about 3 seconds.
U.S. Patent Application Publication 2004/0059393 to Policker et al., which is incorporated herein by reference, describes a method for treating a subject, including receiving a sensor signal responsive to the subject eating, analyzing the sensor signal, and driving a current into tissue of the subject responsive to analyzing the signal. The current is typically driven into muscle tissue of the subject's stomach. Preferably, receiving the sensor signal includes sensing an electrical potential change generated responsive to contraction of a muscle such as a stomach muscle of the subject. In an embodiment, the sensor signal is analyzed with respect to the timing of ingestion, and a level of compliance of the subject with a desired ingestion schedule is determined. As appropriate, a parameter of the current driven into the tissue may be configured such that the application of the current to the tissue induces in the subject a sensation of satiety, discomfort, nausea, or vertigo.
U.S. Pat. No. 6,415,178 and PCT Patent Publication WO 98/10830 to Ben-Haim et al., which are incorporated herein by reference, describe various methods for controlling the behavior of muscle tissue, for example by blocking or altering the transmission of signals therethrough.
PCT Publication WO 05/007232 to Ben Haim et al., which is incorporated herein by reference, describes techniques for treating a subject, including applying an electrical signal to at least one stomach site of the subject. The electrical signal is configured to reduce a rise in a blood glucose level of the subject, in order to treat the subject.
U.S. Pat. No. 6,571,127 and PCT Publication WO 99/03533 to Ben-Haim et al., which are incorporated herein by reference, describe apparatus and methods for applying signals to smooth muscle so as to modify the behavior thereof. In particular, apparatus for controlling the stomach is described in which a controller applies an electrical field to electrodes on the stomach wall so as to modify the reaction of muscle tissue therein to an activation signal, while not generating a propagating action potential in the tissue. In the context of the present patent application and in the claims, the use of such a non-excitatory signal to modify the response of one or more cells to electrical activation thereof, without inducing action potentials in the cells, is referred to as Excitable-Tissue Control (ETC). Use of an ETC signal is described with respect to treating obesity, by applying the ETC signal to the stomach so as to delay or prevent emptying of the stomach. In addition, a method is described for increasing the motility of the gastrointestinal tract, by applying an ETC signal to a portion of the tract in order to increase the contraction force generated in the portion and the stretching of nearby tissue.
U.S. Pat. No. 6,709,388 to Mosse et al., which is incorporated herein by reference, describes a self-propelling device adapted to travel through a passage having walls containing contractile tissue, the device comprising a body and at least one contractile tissue-stimulating means for stimulating the walls to urge the device selectively. The stimulating means may be electrodes, and the passage can be the gut of an animal or human. The device is described as being particularly useful as an enteroscope.
PCT Publication WO 97/31679 to Dirin et al., which is incorporated herein by reference, discloses that USSR Inventor's Certificate No. 1223922, Int. C1, A 61 N 1/36, Bulletin No. 14, by Pekarasky et al., entitled “Gastrointestinal tract electrostimulator,” which is incorporated herein by reference, describes a swallowable capsule adapted for electrostimulation of the alimentary tract, as post-surgical therapy, as a prophylactic measure of treating alimentary tract diseases, or for the promotion of peristalsis, which is further adapted for the dispensing of medication.
PCT Publication WO 97/26042 to Terekhin et al., which is incorporated herein by reference, describes medical equipment that can be used, for example, in post-surgical therapy in outpatient clinics and in hospitals, as well as a prophylactic measure for treating alimentary tract diseases. The equipment is described as an electrical stimulant containing a capsule, in which are located consecutively-connected units for testing parameters of an external medium and a pulse driver, connected to a power supply. Electrodes are provided on the external surface of the capsule, and total in number (2+n), wherein n=0, 1, 2, . . . .
PCT Publication WO 97/31679 to Dirin et al., which is incorporated herein by reference, describes electrostimulation of the gastrointestinal tract. Apparatus is described comprising an olive-like or ovate-cylindrical body member in which at least a part of opposed hemispheres is made conducting and forms a pair of electrodes, as well as a pulse generator and an electric power supply source disposed inside said body member. The apparatus is described as comprising an electrode and means for cyclically reversing the polarity of pulses on the electrodes. Electrostimulation efficiency of the device is described as being independent of opposite preferential orientations of its body member within a given visceral organ of a human being or animal.
PCT Publication WO 04/066903 to Gross et al., which is incorporated herein by reference, describes apparatus for drug administration, including an ingestible capsule. The capsule includes a drug stored by the capsule. An environmentally-sensitive mechanism is adapted to change a state thereof responsive to a disposition of the capsule within a gastrointestinal tract of a subject. A driving mechanism, in response to a change of state of the environmentally-sensitive mechanism, is adapted to drive the drug directly through the endothelial layer of the gastrointestinal tract.
PCT Publication WO 06/018851 to Kliger et al., which is incorporated herein by reference, describes gastric apparatus including one or more sensors, adapted to generate respective sensor signals responsive to activity of a gastrointestinal tract of a subject. A control unit is described as being adapted to receive and analyze the sensor signals and to determine that an eating event has occurred, responsive to at least one of the sensor signals and a threshold. The control unit identifies an aspect of at least one of the sensor signals deriving from rhythmic activity of the gastrointestinal tract that is not indicative or current eating by the subject, and modifies the threshold responsive to the aspect of the signals that derives from activity that is not indicative of current eating. For some applications, the control unit is described as being adapted to modify the threshold if the aspect is indicative of a migrating motor complex (MMC). Other embodiments are also described.